Spanners are tools which are generally used in manufacturing. However the spanner is a large tool so that it cannot be carried conveniently. Thereby there is a great demand for a novel design which can improve the prior art defect.
In one improvement, a driving unit has a receiving portion with a stop surface. A tool head is received in the driving unit. When it is desired to operate the tool, the head is pulled out from the receiving portion, but the stop surface will affect the operation of the tool head. Thereby the type of the tool head is fixed so that the use of the spanner is confined.